The long-term goal of this research program is to develop a general psychobiological model of rote- and rule-learning processes in rat serial-pattern learning. Recent findings suggest that the hippocampal formation is intimately involved in rote serial-pattern learning, whereas other structures of the brain, especially the prefrontal cortex, may mediate cognitive "chunking" processes. The proposed research has two specific aims. The first aim is to further explore the idea that serial pattern learning is subserved by at least two learning/memory systems, namely rote- and rule-learning systems. The second aim is to begin to explore the neural substrates of cognitive "chunking" processes in rat serial-pattern learning. These aims will be accomplished by testing the notion that rote- and rule- learning processes can be dissociated by damage to the hippocampal formation, and by testing the notion that damage to prefrontal cortex results in disruptions of "chunking" processes. The reseach will focus on using established serial-pattern-learning tests to demonstrate the effects of lesioning hippocampus and prefrontal cortex on serial-pattern learning processes. These lines of research will extend our understanding of both cognitive animal learning and memory processes and the neurobiological basis of these processes in the rat brain. This approach offers a potential reapproachment of currently conflicting rote- and rule-based models of sequential learning by distinguishing and characterizing the separate neural substrates subserving these processes. Such a model would also have general implications for models of cognitive and behavioral dysfunction resulting from neurological disorders.